The present application claims priority to Japanese Application(s) No.(s). P2001-236237 filed Aug. 3, 2001, which application(s) is/are incorporated herein by reference to the extent permitted by law.
This invention relates to a technique for allowing a wide band and a high transfer rate to be used and improving a rising characteristic of recording current to reduce the error rate in a signal transmission apparatus and a signal recording apparatus in which a rotary transformer is used.
An apparatus is known that uses a rotary transformer as signal transmission means for transmitting a signal to a rotary system. For example, in a magnetic recording and/or reproduction apparatus in which a rotary head is used, a rotary transformer is used in a circuit which transmits a signal from a drive circuit, which controls recording current, to the rotor side of the recording head.
It is already known that the frequency characteristic of the circuit of the type mentioned depends upon such various factors as the capacitance of active elements such as transistors of an IC (integrated circuit), wiring lines and so forth which form the drive circuit, the inductance, coupling coefficient and floating capacitance relating to the rotary transformer, and the inductance and the capacitance of the head.
Incidentally, if it is attempted to increase the bandwidth and the transfer rate in such a conventional circuit as described, then, for example, such countermeasures as listed below are taken:
(A) To reduce the capacitance;
(B) To raise the coupling coefficient of the transformer; and
(C) To reduce the inductance of the head and/or the rotary transformer.
However, the countermeasure (A) is impractical because the capacitance relies almost upon the devices used and therefore there remains little room for improvement.
Meanwhile, the countermeasure (B) gives rise to a problem of, for example, a drawback that raising of the coupling coefficient increases the cost upon mass production.
Further, the countermeasure (C) has a fixed limit because the reduction of the inductance gives rise to problems of increase of recording current, drop of the recording efficiency and so forth.
Accordingly, even if trial and error is repeated combining the countermeasures mentioned above suitably, it is difficult to achieve a sufficient transmission characteristic or recording characteristic.
It is an object of the present invention to provide a signal transmission apparatus and a signal recording apparatus using a rotary transformer, which is capable of using a wide bandwidth and a high transfer rate, without a significant increase of the cost or a bad influence on signal recording.
In order to attain the object described above, according to an aspect of the present invention, there is provided a signal transmission apparatus in which a rotary transformer is used, including a transmission side circuit including a drive circuit and a reception side circuit including a load, the rotary transformer being interposed between the transmission side circuit and the reception side circuit, and a passive element circuit including an inductance element and connected to an input stage of the rotary transformer in parallel to the rotary transformer, the passive element circuit having an inductance value set equal to or lower than an equivalent inductance value when the circuit of the rotary transformer side is viewed from the transmission side circuit.
With the signal transmission apparatus, only by providing a passive element circuit including an inductance element at the input stage of the rotary transformer, the bandwidth and the transmission efficiency can be improved without involving a significant increase of the cost.
According to another aspect of the present invention, there is provided a signal recording apparatus in which a rotary transformer is used, including a transmission side circuit and a reception side circuit between which the rotary transformer is interposed, the transmission side circuit being provided on the stator side of the rotary transformer while the reception side circuit is provided on the rotor side of the rotary transformer, the transmission side circuit including a recording circuit while the reception side circuit includes a recording head or a recording head and a reproduction amplifier such that an output signal of the recording circuit is transmitted to the recording head of the reception side circuit through the rotary transformer, and a passive element circuit including an inductance element and connected to an input stage of the rotary transformer in parallel to the rotary transformer, the passive element circuit having an inductance value set equal to or lower than an equivalent inductance value when the circuit of the rotary transformer side is viewed from the transmission side circuit.
With the signal recording apparatus, the recording bandwidth is expanded when compared with that of a conventional signal recording apparatus. Consequently, improvement in error rate, that is, reduction of the error rate, by an effect of improvement of the recording signal waveform can be achieved, and therefore, higher density recording can be anticipated.